This invention relates to box hole drill steel.
Box hole drill steel and a method of its use is disclosed in U.S. Pat. No. 3,917,321.
Dual tube drill pipe with the inner tube elastomer mounted in the outer tube has heretofore been used, e.g. in drilling vertical holes for support posts, and is disclosed in the U.S. Pat. No. 4,067,596, by Jackson M. Kellner and Vincent Hugo Vetter entitled "Dual Flow Passage Drill Stem", assigned to the same assignee as the present invention. Multiple tube drill pipe having an elastomer mounted inner tube and intended primarily for drilling horizontal and near horizontal holes, e.g. for venting methane from coal mines, is disclosed in U.S. Pat. No. 4,040,495, by Jackson M. Kellner and William R. Garrett, entitled "Hydro-Electric Bit Guide", assigned to the same assignee as the present application. Other prior art relevant to multiple pipe and to elastomer mounting of the inner tube thereof is discussed in these two Kellner et al patent applications and should be consulted for further identification of the prior art.
Dust suppression has heretofore been effected in box hole drill steel, e.g. it is understood, by providing each length of box hole steel with a water conduit, probably a rubber hose therein, the hoses being provided at their ends with steel couplings.
Box hole drill steel with dust suppressant water pipe welded solidly in the center thereof and with pin and box O-ring sealed telescopic joints at the ends of the pipe has heretofore been made.
Box hole drill steel with flanges for handling the steel and splines for making a driving connection with the drill steel may be the subject of a pending application assigned to the same assignee as the present invention by inventors employed by another division of the assignee.
Double lip elastomer seal rings with O-ring spreaders, all of the same construction as used herein for support rings, are known as Parker rod seals.
Dual tube drill pipe, with an elastomer shock absorber and telescopic, elastomer sealed connection means for the inner tube thereof are disclosed in U.S. Pat. Nos. 4,012,061 by Wallace F. Olson and 3,998,479 by William W. Bishop, both assigned to the same assignee as the present application, and considerable prior art relating thereto is made of record therein.